Draconian “unusually severe or cruel” is based on Latin Dracō (stem Dracōn-), plus the adjectival suffix -ian. In ancient Athens, a city-state that is now the capital of Greece, Draco (known to his fellow Athenians as Drákōn) was a statesman who was famous—or infamous—for the unusually harsh laws he enacted around 621 BC. 

According to the Oxford English Dictionary, the first recorded use of "draconian" in English was around the 1870s, with the earliest evidence cited from 1876 in the writings of Charles M. Davies.